Additive for coating compositions

ABSTRACT

An additive for coating compositions which is a blend of 
     (A) 20-50% by weight of a polyisocyanate having the formula ##STR1##  where R 1  is (CH 2 ) 6&#39;  (B) 1-15% by weight of an ester of a polyalkylene glycol alkyl alkylate, an alkyl phthalate or an alkyl aromatic phthalate 
     (C) 1-10% by weight of a blend of ultraviolet light stabilizers and 
     (D) 25-78% by weight of organic solvent; the additive can be added to acrylic lacquers, nitrocellulose lacquers, acrylic-alkyd enamels and acrylic polyurethane enamels to provide flexible finishes for flexible substrates used in automobile and truck bodies.

BACKGROUND OF THE INVENTION

This invention relates to an additive for coating compositions whichimparts flexibility to finishes formed from coating compositioncontaining the additive.

For painting and refinishing of automobiles and trucks, the followingpaints are sold: acrylic lacquers as described in Meyer U.S. Pat. No.4,168,249 issued Sept. 18, 1979, nitrocellulose lacquers, acrylic alkydenamels as described in Miller U.S. Pat. No. 3,844,993 issued Oct. 29,1974 and acrylic polyurethane enamels as described in Vasta U.S. Pat.No. 3,558,564 issued Jan. 26, 1971. The lacquers and enamels have a lowlevel of flexibility and are primarily designed for application overrigid metal parts of automobiles and trucks. However, there are a numberof parts of automobile and truck bodies that use flexible materials suchas the flexible material covering the area between the bumper and thebody of an automobile. When the aforementioned enamels or lacquers areapplied over this flexible material, upon flexing, they crack, chip andpeel off. A universal additive is needed that would form flexiblefinishes of these enamels and lacquers but would not degrade otherimportant properties such as adhesion, weatherability, gasolineresistance, gloss and distinctness of image.

SUMMARY OF THE INVENTION

An additive for coating compositions which is a mixture of about

(A) 20-50% by weight of a polyisocyanate of the formula ##STR2## whereR¹ is (CH₂)₆, (B) 1-15% by weight of an ester selected from the group ofa polyalkylene glycol alkyl alkylate, an alkyl phthalate or an alkylaromatic phthalate,

(C) 1-10% by weight of a blend of ultraviolet light stabilizers and

(D) 25-78% by weight of an organic solvent.

DESCRIPTION OF THE INVENTION

The additive of this invention can be blended with the following coatingcompositions: acrylic lacquers, nitrocellulose lacquers, acrylic alkydenamels and acrylic polyurethane enamels and provides finishes withexcellent flexibility. The additive does not degrade other properties ofthese finishes such as gloss, adhesion, weatherability and gasolineresistance. Typically useful lacquer and enamel coating compositions aredescribed in the aforementioned patents to Meyer, Miller and Vasta andthe disclosure of these patents is hereby incorporated by reference.

Usually about 10-100% by weight, based on the weight of the coatingcomposition, of the additive is blended with the coating composition.Preferably, about 20 to 70% by weight of the additive is used.Generally, about 2 parts by weight of acrylic or nitrocellulose lacquerare used per 1 part additive, 8 parts by weight acrylic alkyd enamel per1 part of additive are used and 4 parts by weight of acrylicpolyurethane enamel per 1 part additive are used.

The addition of the additive decreases the "pot" life of the coatingcomposition. Generally, the aforementioned lacquers containing theadditive must be used within about 4 hours after addition of theadditive before the lacquer increases in viscosity or gels. The aboveenamels have a "pot" life of about 8 hours after addition of theadditive.

The additive contains about 20-50% by weight, based on the weight of theadditive, of a polyisocyanate of the formula ##STR3## where R¹ is(CH₂)₆, Preferably, about 25 to 40% by weight of the polyisocyanate isused.

The additive contains 1-15% by weight, based on the weight of theadditive of a polyalkylene glycol alkyl acrylate, an alkyl phthalate oran alkyl aromatic phthalate. Preferably, about 4 to 10% by weight of thepolyalkylene glycol alkyl acrylate are used. Typically, polyethyleneglycol di(2-ethylhexoate) is used. A typical alkyl phthalate that can beused is dioctyl phthalate and a typical alkyl aromatic phthalate isbutyl benzyl phthalate.

The additive contains about 1-10% by weight based on the weight of theadditive, of ultraviolet light stabilizers. Preferably, 5 to 10% byweight of ultraviolet light stabilizers are used.

Typical ultraviolet light stabilizers that are useful in the additiveare as follows:

Benzophenones such as hydroxydodecycl benzophenone,2,4-dihydroxybenzophenone, hydroxybenzophenones containing sulfonic acidgroups, 2,4-dihydroxy-3',5'-di-t-butylbenzophenone,2,2',4'-trihydroxybenzophenone esters of dicarboxylic acids,2-hydroxy-4-acryloxyethoxybenzophenone, aliphatic mono-esters of2,2',4-trihydroxy-4'-alkoxybenzophenone,2-hydroxy-4-methoxy-2'-carboxybenzophenone;

Triazoles such as 2-phenyl-4-(2'-4'-dihydroxybenzoyl)triazoles,substituted benzotriazoles such as hydroxyphenyltriazoles such as2-(2'-hydroxy-5'-methylphenyl)benzotriazole,2-(2'-hydroxyphenyl)benzotriazole,2-(2'-hydroxy-5'-octylphenyl)naphthotriazole;

Triazines such as 3,5-dialkyl-4-hydroxyphenyl derivatives of triazine,sulfur-containing derivatives of dialkyl-4-hydroxyphenyltriazines,hydroxyphenyl-1,3,5-triazines and such triazines containing sulfonicacid groups, aryl-1,3,5-triazines, orthohydroxyaryl-s-triazine;

Benzoates such as dibenzoate of diphenylolpropane, t-butyl benzoate ofdiphenylolpropane, nonyl phenyl benzoate, octyl phenyl benzoate,resorcinol dibenzoate.

Other ultraviolet light stabilizers that can be used include lower alkylthiomethylene-containing phenols, substituted benzenes such as1,3-bis(2'-hydroxybenzoyl)benzene, metal derivatives of3,5,-di-t-butyl-4-hydroxyphenylpropionic acid, asymmetrical oxalic aciddiarylamides, alkylhydroxyphenylthioalkanoic acid esters,dialkylhydroxyphenylalkanoic acid esters of di- and tri-pentaerythritol,phenyl- and naphthlene-substituted oxalic acid diamides,methyl-β-(3,5-di-t-butyl-4-hydroxyphenyl)propionate,α,α'-bis(2-hydroxyphenyl)diisopropylbenzene,3,5'-dibromo-2'-hydroxyacetophenone, ester derivatives of4,4-bis(4'-hydroxyphenyl)pentanoic acid wherein there is at least oneunsubstituted position ortho to the aromatic hydroxyl groups,organophosphorus sulfides such asbis(diphenylphosphinothioyl)monosulfide andbis(diphenylphosphinothioyl)disulfide,4-benzoyl-6-(dialkylhydroxybenzyl)resorcinol,bis(3-hydroxy-4-benzoylphenoxy)diphenylsilane,bis(3-hydroxy-4-benzoylphenoxy)dialkylsilane, 1,8-naphthalimides,α-cyano-β,β-diphenylacrylic acid derivatives,bis(2-benzoxazolyl)alkanes, bis(2-napthoxazolyl)alkanes, methylenemalonitriles containing aryl and heterocyclic substitutes,alkylenebis(dithio)carbamate, 4-benzoyl-3-hydroxyphenoxyethyl acrylate,4-benzoyl-3-hydroxyphenoxyethyl methacrylate, aryl- or alkyl-substitutedacrylonitriles, 3-methyl-5-isopropylphenyl-6-hydroxycoumarone.

Particularly useful ultraviolet light stabilizers that can be used arehindered amines of piperidyl derivatives such as those disclosed inMurayama et al., U.S. Pat. No. 4,061,616, issued Dec. 6, 1977, column 2,line 65, through column 4, line 2, and nickel compounds such as[1-phenyl-3-methyl-4-decanoylpyrazolate(5)]-Ni,bis[phenyldithiocarbamato]-Ni(II), and others listed in the abovepatent, column 8, line 44 through line 55.

The following blend of ultraviolet light stabilizers is particularlypreferred 2-[2'-hydroxy-3',5'-1(1-1-dimethyl-propyl)phenyl]benzotriazoleand di-[4-(2,2,6,6,-tetramethylpiperidyl)]sebecate. The stabilizers canbe used in any ratio however, a 2:1 ratio of benzotriazole to sebecateis preferred.

The additive contains about 25-78% by weight, based on the weight of theadditive of organic solvents. Preferably, about 40 to 66% by weight oforganic solvents are used. Typically useful solvents are toluene,xylene, ethyl acetate and other organic solvents that do not containhydroxyl groups or carboxyl groups.

After the additive is blended with a coating composition, the resultingblend is applied by conventional technique such as spraying,electrostatic spraying, brushing, dipping and the like to a substrateand dried at ambient temperatures. Typical flexible substrates to whichthese compositions can be applied are flexible thermoplasticpolyurethane and injection molded polyurethanes. Low baking temperaturesof 50°-125° C. can also be used to force dry the composition. Theresulting finishes have good flexibility and retain the other goodproperties of the composition to which they were added.

The following examples illustrate the invention. All parts andpercentages are on a weight basis unless otherwise indicated.

EXAMPLE 1

The following constituents were blended together to form the additive ofthis invention:

    ______________________________________                                                          Parts By                                                                      Weight                                                      ______________________________________                                        Ethyl acetate       70.51                                                     Diethylene glycol monobutyl                                                                       7.90                                                      ether                                                                         Toluene             74.03                                                     Polyethylene glycol di                                                                            10.52                                                     (2-ethylhexoate)                                                              2-[2'-hydroxy-3',5'-1(1-1-                                                                        7.88                                                      dimethyl-propyl)phenyl]                                                       benzotriazole                                                                 Di-[4-(2,2,6,6,-tetramethyl-                                                                      3.95                                                      piperidyl)]sebacate                                                           Desmodur ® L2291-trimer of                                                                    92.18                                                     hexamethylene diisocyanate                                                    Total               266.97                                                    ______________________________________                                    

A white acrylic lacquer was prepared by blending together the followingingredients:

    ______________________________________                                                             Parts By                                                                      Weight                                                   ______________________________________                                        Mixed methyl esters of 16.71                                                  succinic, glutaric and adipic acids                                           Isopropanol            22.34                                                  Xylene                 31.97                                                  Alkyd Resin Solution (85%                                                                            36.60                                                  solids in toluene of an                                                       alkyd resin of coconut oil/                                                   ethylene glycol/phthalic                                                      anhydride having a Gardner                                                    Holdt Viscosity of Y-Z,                                                       measured at 25° C. and an acid                                         number of about 7-10)                                                         Silicone Solution (1% solids in                                                                      0.17                                                   Xylene of Silicone SF69)                                                      Polymethyl methacrylate Solution                                                                     37.38                                                  (40% solids in a mixture of                                                   toluene/acetone of polymethyl                                                 methacrylate having a relative                                                viscosity of 1.19 measured on                                                 a 0.5% polymer solids solution                                                using dichloroethylene solvent                                                at 25° C.)                                                             Methyl methacrylate/diethyl                                                                          67.40                                                  amino ethyl methacrylate                                                      copolymer solution (40% solids                                                in a mixture of toluene/acetone                                               of a copolymer of 99% methyl                                                  methacrylate and 1% diethyl                                                   amino ethyl methacrylate having a                                             relative viscosity of 1.2 measured                                            as above.)                                                                    Methyl methacrylate /butyl                                                                           109.90                                                 acrylate copolymer solution                                                   (40% solids in a mixture of                                                   toluene/acetone of a copolymer                                                of 82% methylmethacrylate 18%                                                 butylacrylate having a relative                                               viscosity of 1.19 measured as                                                 above.)                                                                       Iminated Polymer Solution                                                                            11.36                                                  (39% solids in toluene/isopropanol                                            of a polymer of methyl methacrylate/                                          ethyl acrylate/methacrylic acid/                                              propyleneimine in a weight ratio of 1                                         81/14.6/4.4/2.9 and the polymer has                                           a relative viscosity measured as                                              above of 1.2)                                                                 Cellulose Acetate Butyrate                                                                           41.83                                                  (CAB) solution (20% CAB                                                       having a 37% butyryl                                                          content and a viscosity                                                       of 20 seconds in a solvent                                                    of acetone and ethanol)                                                       CAB Solution (20% CAB having                                                                         70.58                                                  a butyryl content of 37%                                                      and a viscosity of 2 seconds                                                  in a solvent of acetone and                                                   ethanol)                                                                      White Mill Base (55% titanium                                                                        109.12                                                 dioxide pigment, 8% acrylic                                                   resin and 37% solvent of                                                      toluene and "Cellosolve"                                                      acetate                                                                       Yellow Mill Base (22% yellow                                                                         1.11                                                   iron oxide pigment, 19%                                                       acrylic resin and 59% toluene                                                 Total                  556.02                                                 ______________________________________                                    

About 67 parts of the above white acrylic lacquer and 33 parts of theabove additive were blended together to form Paint 1 and sprayed onto athermoplastic polyurethane flexible substrate and dried tack free atambient temperature in 15 minutes. The gloss, distinctness of image,flexibility at room temperature and at -28° C. and gasoline resistancewas measured and the panel was then exposed to outdoor weathering inFlorida for 6 months and the gloss at 60° was measured and % glossretention was determined. The results of these tests are recorded in theTable.

The following paints were formulated using commercial products which areused to improve flexibility of finishes.

    ______________________________________                                        Paint A                                                                       1 Part  Du Pont Additive (22% solids                                                  of 12 parts polymer of methyl                                                 methacrylate/3-(2-methacryloxy ethyl)-                                        2,2-spiro cyclohexyl oxazolidene                                              95/5 ratio, 48 parts of polymer of                                            methyl methacrylate/butyl acrylate                                            85/15 ratio, 40 parts butyl benzyl                                            phthalate in a solvent of acetone and isoproponol)                    1 Part  White acrylic lacquer                                                         (prepared above)                                                      Paint B                                                                       1 Part  Morton's Impact Coating                                                       (31% solids of 72 parts polymer                                               of methyl methacrylate/butyl acrylate/                                        butyl methacrylate/hydroxy propyl                                             methacrylate 66/11/17/4 ratio,                                                18 parts polyester of butylene glycol/                                        ethylene glycol and lauric/myristic/                                          palmitic/stearic/oleic/adipic/o-phthalic                                      acids, ratio of acids to glycol is                                            3/1 and the polyester has a weight                                            average molecular weight of 13,000                                            and 10 parts dioctyl phthalate in a                                           solvent of toluene and "Cellosolve")                                  1 Part  White acrylic lacquer                                                         (prepared above)                                                      Paint C                                                                       1 Part  Inmont's Additive (19% solids of                                              polyester or dipropylene glycol                                               adipate chain extended with 1,6-                                              hexamethylene diisocyanate and                                                having a weight average molecular                                             weight of 23,000 in a solvent of ethyl                                        acetate and "Cellosolve")                                             1 Part  White acrylic lacquer                                                         (prepared above)                                                      Paint D                                                                       1 Part  Ditzler's Additive (50% solids of                                             a resin of polycaprolactone, poly-                                            propylene glycol and 3,-isocyanato-                                           methyl-3,3,5-trimethyl cyclohexyl                                             isocyanate in a molar ratio of                                                about 50/50/2, the resin is isocyanate                                        terminated and has a weight average                                           molecular weight of 23,000 in a solvent                                       of methyl ethyl ketone and toluene)                                   4 Parts White acrylic lacquer                                                         (prepared above)                                                      ______________________________________                                    

Each of the above paints A-D were each applied to a separate flexiblesubstrate described above as the paint made with the additive of thisinvention and dried tack free at ambient temperature and gloss,distinctness of image, flexibility at room temperature at -28° C. andgasoline resistance for each was measured and 60° gloss retention wasdetermined after 6 months outdoor weather in Florida. The results areshown in the Table.

The gloss and distinctness of image (DOI) of all the paints was aboutequivalent. The flexibility of Paint 1 containing the additive of theinvention was better than Paint A and about equivalent to the otherpaints and the flexibility of Paint 1 at -28° C. was equal to Paint Dand better than the other paints. The gasoline resistance of Paint 1 wasbetter than the other paints. The outstanding feature is that Paint 1has substantially better gloss retention after exposed to outdoorweathering in Florida for 6 months in comparison to the Paints A-D.

                                      TABLE                                       __________________________________________________________________________                                   Gaso-                                                                             60° Gloss                                                 Flex.    line                                                                              Retention                                            DRY Gloss   Room     Resis-                                                                            6 mos.                                     Additive  TIME                                                                              20°                                                                      60°                                                                      DOI*                                                                              Temp.                                                                             -28° C.                                                                     tance                                                                             Florida                                    __________________________________________________________________________    Paint 1                                                                       Invention Additive                                                                      15 min.                                                                           52                                                                              84                                                                              50  9   8    5   71%                                        Paint A                                                                       Du Pont Additive                                                                        15 min.                                                                           58                                                                              83                                                                              50  7   7    4   48%                                        Paint B                                                                       Morton    15 min.                                                                           56                                                                              81                                                                              50  10  5    4   34%                                        Paint C                                                                       Inmont's Additive                                                                       15 min.                                                                           53                                                                              81                                                                              50  10  6    3   33%                                        Paint D                                                                       Ditzler's Additive                                                                      15 min.                                                                           52                                                                              80                                                                              50  9   8    4   27%                                        __________________________________________________________________________     *DOI -- Distinctness of Image                                                 Ratings                                                                       Flexibility -- 10 -- excellent no cracks, 7 acceptable, below 7               unacceptable                                                                  Gasoline Resistance -- 5 -- excellent, 3 acceptable -- some paint peeling     off, below 3 unacceptable                                                

EXAMPLE 2

A black nitrocellulose lacquer was prepared by blending together thefollowing constituents:

    ______________________________________                                                            Parts By                                                                      Weight                                                    ______________________________________                                        Isopropanol           22.19                                                   Xylene                10.71                                                   Toluene               68.11                                                   Aromatic petroleum naphtha                                                                          7.43                                                    Blown castor oil      0.82                                                    Copper naphthenate    0.97                                                    Alkyd resin solution  10.15                                                   (described in Example 1)                                                      Carbon black mill base                                                                              47.56                                                   (11% carbon black, 30%                                                        acrylic resin 60% solvent of                                                  toluene/isopropanol)                                                          Nitrocellulose (1/2 second                                                                          80.82                                                   viscosity dehydrated with                                                     isopropanol)                                                                  Nitrocellulose (5-6 second                                                                          13.48                                                   viscosity dehydrated with                                                     isopropanol)                                                                  Ethylene glycol monoethyl                                                                           23.06                                                   ether acetate                                                                 Butyl acetate         33.01                                                   Methy isobutyl ketone 7.53                                                    Acetone               117.06                                                  Butyl benzyl phthalate                                                                              23.73                                                   Trixylene phosphate   2.87                                                    Copolymer solution    39.72                                                   (43% solids copolymer of                                                      methyl methacrylate/butyl acrylate                                            in solvents of acetone/toluene)                                               Silicone solution (20%                                                                              3.28                                                    silicone resin in xylene)                                                     Total                 512.50                                                  ______________________________________                                    

About 264.5 parts of the additive of this invention, prepared in Example1, were blended with the above black lacquer and the resultingcomposition was sprayed onto a thermoplastic polyurethane flexiblesubstrate and dried in 15 minutes to a tack free state at ambienttemperatures. The gloss at 20° was 64, at 60° 91 and the distinctness ofimage was 40. The flexibility at room temperature was 9 and at -28° C.was 8. Gasoline resistance was 4. 60° gloss retention after 6 monthsweathering in Florida was 90%. The same tests and ratings were used inExample 1.

EXAMPLE 3

A white alkyd-acrylic resin paint was formulated by blending thefollowing constituents:

    ______________________________________                                                           Parts By                                                                      Weight                                                     ______________________________________                                        Alkyd resin solution 199.51                                                   (55% solids of a coco-                                                        nut oil/dehydrated castor oil                                                 fatty acids-pentaerythritol/                                                  benzoic acid-pentaerythritol/                                                 phthalic anhydride/with excess                                                pentaerythritol in a weight ratio                                             of 4.6/41.2/10.0/38.9/6.5)                                                    White mill base (58% titanium                                                                      176.03                                                   dioxide pigment, 15% acrylic                                                  resin, 27% aromatic solvent)                                                  Yellow mill base (40% ferric                                                                       0.63                                                     yellow pigment, 22% acrylic                                                   resin, 38% xylene)                                                            Black mill base (12% carbon                                                                        0.21                                                     black pigment, 31% acrylic                                                    resin, 56% xylene)                                                            Acrylic vinyl oxazoline                                                                            165.52                                                   polymer solution (59%                                                         polymer solid of polymer of                                                   methyl methacrylate, butyl                                                    methacrylate, hydroxy ethyl                                                   methacrylate, diethyl                                                         amino ethyl methacrylate                                                      and vinyl oxazoline ester                                                     of linseed oil fatty acids                                                    in weight ratio of 40/33/                                                     7/5/15 in toluene)                                                            Cobalt Drier Solution                                                                              5.82                                                     Xylene               69.59                                                    VM&P naphtha         43.52                                                    Turpentine           6.66                                                     Aromatic hydrocarbon 33.29                                                    Total                700.70                                                   ______________________________________                                    

About 160 parts of the additive of this invention, prepared in Example1, were blended with the above with alkyd acrylic resin paint and theresulting composition was sprayed onto a thermoplastic polyurethaneflexible substrate and dried in 30 minutes to a tack free state atambient temperatures. The gloss at 20° was 80, at 60° 90, flexibility atroom temperature was 10 and at -28° C. was 8. Gasoline resistance was 4.60° Gloss retention after 6 months weathering in Florida was 84%. Thesame tests and ratings were used as in Example 1.

I claim:
 1. An additive for coating compositions which comprisesabout:(A) 20-50% by weight of a polyisocyanate having the formula##STR4## where R¹ is (CH₂)₆, (B) 1-15% by weight of polyethylene glycoldiethyl hexoate, (C) 1-10% by weight of a blend of ultraviolet lightstabilizers comprising a benzotriazole ultraviolet light stabilizer anda hindered amine light stabilizer, and (D) 25-78% by weight of organicsolvent.
 2. The additive of claim 1 in which the blend of ultravioletlight stabilizers consists essentially of2-[2'-hydroxy-3'5'-1(1-1-dimethyl-propyl)phenyl]benzotriazole anddi-[4-(2,2,6,6-tetramethylpiperidyl)]sebacate.
 3. The additive of claim1 in which the organic solvent comprises ethyl acetate, toluene anddiethylene glycol monobutyl ether.
 4. A coating composition containing10-70% by weight of a binder and 90-30% by weight of a liquid carrierand containing about 10-100% by weight, based on the weight of thecoating composition of the additive of claim
 1. 5. The coatingcomposition of claim 4 in which the composition contains pigments in apigment to binder weight ratio of about 1:100 to 200:100.
 6. The coatingcomposition of claim 5 in which the binder comprises an acrylic polymer.7. The coating composition of claim 5 in which the binder comprises anitrocellulose polymer.
 8. The coating composition of claim 5 in whichthe binder comprises an acrylic vinyl oxazoline ester polymer.
 9. Thecoating composition of claim 4 in which the binder comprises an acrylicresin containing reactive hydroxyl groups and a polyisocyanatecrosslinking resin.
 10. A flexible substrate coated with the compositionof claim
 4. 11. The flexible substrate of claim 10 in which thesubstrate is a thermoplastic polyurethane.
 12. The flexible substrate ofclaim 10 in which the substrate is an injection molded polyurethane.